Biomass energy derives from the ability of plants to use photosynthesis to convert solar energy into chemical energy and store that energy. Bioenergy provides nearly 15% of the world's total energy consumption and is the fourth-largest energy source after oil, coal, and natural gas. Bioenergy is the only form of renewable energy that can be collected, stored, and transported. It has widespread availability, is environmentally friendly, and has nearly zero carbon emissions, which are all important aspects of the six kinds of renewable energy. However, the biomass resource is a scattered resource with low energy density and is less efficient for storage and transportation, which delays its large-scale utilization.
Biomass briquette fuel (BBF) technology involves compressing unshaped raw materials into shaped and higher-density briquettes by drying, chopping, and forming processes, thereby reducing transportation and storage costs, improving the combustion quality, and generally expanding the scope of its application. BBF can be used not only for biomass gasification power generation, direct combustion power generation, and co-combustion power generation but also for industrial boilers, furnaces, and heating boilers, for example. Using BBF technology can realize energy savings from non-renewable resources such as coal and petroleum, improve the energy consumption structure, and reduce emissions of CO2 and SO2 to alleviate environmental pollution, promote new rural construction, achieve important energy savings, and expand the development of a low-carbon economy.
Biomass closely resembles coal in its physical and chemical characteristics. Therefore, using BBF with coal in combustion power generation is a reasonable use of biomass resources and reduces coal combustion pollution. Biomass and coal co-combustion power generation can not only relieve the pressure on non-renewable energy resources but can also resolve the instability of biomass power generation caused by seasonal variation in the availability of the biomass resource.
The biomass material must be stored after the agricultural residues have been crushed and before it is used in BBF and coal-based co-combustion power generation technology. Storage of the biomass material is the basic process that ensures stability and continuity of the co-combustion power generation operation. However, the density of the biomass material in a bin will change due to the shape, size, viscosity, moisture, density, flow, and porosity characteristics of the biomass material itself. It is difficult to transport a biomass material out of a biomass material bin. The limitation of the present material stirring systems is that the electrically powered systems are easily overloaded and damaged during prolonged use due to the cohesive tendency of the materials as well as when the material moisture content is too high and/or when the biomass material has low porosity.